FIG. 1 is a systematic diagram of a conventional LED display system 100 for advertising board applications, which includes an AC/DC converter 102 to provide 5V power for a display panel 104. The display panel 104 includes LED light sources 106, 110 and 114 and drivers 108, 112 and 116 to drive the LED light sources 106, 110 and 114, respectively. Each LED light source 106 includes multiple LEDs 118, each LED light source 110 includes multiple LEDs 120, and each LED light source 114 includes multiple LEDs 122. Both of the LEDs 118 and 120 have a forward voltage of about 2.2V, the LED 122 has a forward voltage of about 3.6V, the AC/DC converter 102 provides a supply voltage of 5V, and therefore, to avoid the residue in the supply voltage makes the LEDs 118, 120 and 122 over heated to be damaged, each of the LEDs 118, 120 and 122 is serially connected with a respective resistor Rc serving a heat sinker to share heat that would be generated by the LEDs 118, 120 and 122.
However, there is a distance between the AC/DC converter 102 and the display panel 104, and thus the resistance Rp of the power lines and the resistance Rg of the ground lines between the AC/DC converter 102 and the display panel 104 will induce a lot of power consumption. In addition, the heat sinker resistors Rc also induce a lot of power consumption. That is, because of the resistances Rp, Rg and Rc, there will be low efficiency and large power consumption in the conventional LED display system 100. Moreover, in the conventional LED display system 100, too much heat induces the degradation of LED performance.
Therefore, it is desired a high efficiency power system for a LED display system.